Cosmological Properties of a Gauged Axion

TL;DR

This paper explores the cosmological implications of gauged axions in models with anomalous U(1) symmetries, focusing on their potential as dark matter candidates and their interactions with gauge fields.

Contribution

It introduces a framework for analyzing gauged axions with anomalous U(1) symmetries, including their relic densities and role in dark matter.

Findings

Gauged axions can contribute significantly to dark matter relic density.

Models with a single anomalous U(1) generally do not explain dark energy.

Sequential misalignments at phase transitions affect axion properties.

Abstract

We analyze the most salient cosmological features of axions in extensions of the Standard Model with a gauged anomalous extra U(1) symmetry. The model is built by imposing the constraint of gauge invariance in the anomalous effective action, which is extended with Wess-Zumino counterterms. These generate axion-like interactions of the axions to the gauge fields and a gauged shift symmetry. The scalar sector is assumed to acquire a non-perturbative potential after inflation, at the electroweak phase transition, which induces a mixing of the Stuckelberg field of the model with the scalars of the electroweak sector, and at the QCD phase transition. We discuss the possible mechanisms of sequential misalignments which could affect the axions of these models, and generated, in this case, at both transitions. We compute the contribution of these particles to dark matter, quantifying their relic densities as a function of the Stuckelberg mass. We also show that models with a single anomalous U(1) in general do not account for the dark energy, due to the presence of mixed U(1)-SU(3) anomalies.